Human Genome Project (1 Viewer)

[malkin86]

Just thought I'd do a little sharing..

Goals
– detailed maps of the genes in the human genome
- Determining the complete nucleotide (base) sequence of DNA of each gene (e.g. GAC)
- Identifying the genetic variation in the human genome
- Identifying and addressing the ethical, legal and social issues related to the HGP.

Limitations
- Data from the HGP are in the form of base sequences (e.g. GAC GGG GGC AAT GCT) and are meaningless on their own – they need to be interpreted.
- A small proportion of the base sequence of each chromosone consists of genes, so it is necessary to search the sequence for possible genes. After identifying a possible gene the next tasks include identifying the protein made from the gene, finding where the gene is expressed in the human body, what does the gene control, when and under what conditions is the gene active.
- To identify possible genes from the DNA sequence data, the scientists search the sequences for lengths of DNA that correspond to possible genes. The rapid scanning of base sequences has been made feasible through the use of computers and specialised software. Genes vary in size, but an average gene consists of several thousand bases.
- A possible gene is a sequence of dna that begins with a start triplet (TAC or GTA), can be read in successive triplets that code for at least 100 amino acids without stopping, ends with a stop triplet (ACT, ATT, or ATC). After identifying the gene, a protein product must be identified and its function.

 

[nesstar]

Does anybody know the answer to this related dot point:

"process information from secondary sources to assess the reasons why the Human Genome project could not be achieved by studying linkage maps"

 

[xiao1985]

Does anybody know the answer to this related dot point:

"process information from secondary sources to assess the reasons why the Human Genome project could not be achieved by studying linkage maps"

breading human is unethical
too big of a map to be mapped using linkage maps...

 

[malkin86]

Um, what's a linkage map?

 

[nik_noodle]

i covered the same point today (cause my teacher is too slack to bother doing it, ive done my own notes all year and reached this point at the uni this arvo. and this was what i ended up with on linkage maps, well a summary of it anyway. my notes r on the other puty now.

Linkage maps do not give the exact location of specific genes, nor do they provide nucleotide sequencing.
Therefore they are insufficient to complete the human genome as the projects primary goals include producing a set of maps of not only the relative positions, but also the exact position of genes on a chromosome and their base sequences.

I may be wrong.......?
Love Nikki

 

[the_archduke]

We haven't even touched on the Human Genome Project. Exactly how far into the Genetics elective are all of you? I think we might be behind.

 

[Tommy_Lamp]

thats useful, thanks

 

[silvermoon]

why the HGP couldnt be achieved using linkage maps

The primary goal of the HGP is to create a series of maps, of each human chromosome, at increasingly finer resolutions.
Mapping is the process of determining the position and spacing of genes on the chromosomes. The mapping used in deciphering the human genome involves;
1. Locating chromosomes (Genetic Mapping)
2. Locating exact position of each gene on a chromosome (Physical Mapping)
3. Determining nucleotide sequence of each gene (DNA Sequencing)
The coarsest resolution of gene maps are genetic linkage maps which depict the relative chromosomal locations of DNA markers by their patterns of inheritance. Physical maps determine chemical characteristics of the DNA molecule, whilst DNA sequencing determines the nucleotide sequence of the gene.

1. Genetic Mapping
Genetic maps are used to identify genes associated with genetic diseases and other biological properties. Genetic maps also form the scaffold that is needed for physical mapping. Methods of genetic mapping include; recombinant DNA cloning techniques, nucleic acid hybridisation and autoradiography.
Genetic maps are constructed by determining how frequently two ‘markers’, eg a physical trait of a particular syndrome, are inherited together.
The closer the genes lie on a chromosome the higher the chance they have of being inherited together. The distance between genes is measured in centrimorgans (cM).

2. Physical Mapping
Physical mapping determines the physical distance between landmarks on the chromosome. Extracting DNA from human chromosomes and randomly breaking it into fragments using restriction enzymes establish these maps. Clones are then made of these fragments, so that each can be tested for the presence or absence of specific genetic landmarks, this is done by running the chromosome on an electrophoresis gel. Clones, which share several landmarks, are likely to come from overlapping segments of chromosomes. Overlapping regions can be compared to determine the overall order of the landmarks along the chromosome and the exact sequence in which the cloned pieces of DNA originally existed in the chromosome. The positions of coding and non-coding DNA are located along each chromosome.

3. DNA Sequencing
DNA sequencing is the process of determining the sequence of bases in the DNA composing a gene. The gene to be sequenced is firstly cloned by recombinant DNA and prepared as a single strand of DNA- this strand is made complementary to the gene using a mixture of nucleotides and DNA polymerase, also added to this mixture is dideoxyribonucleotide, which like nucleotides has four versions- dd ATP, dd TTP, dd CTP and dd GTP. This dd nucleotide is used as it is made in a radioactive form and shows up in autoradiography and it also stops DNA synthesis when inserted into the DNA structure.
These ingredients are mixed in either test-tubes or autoanalysers. The result are fragments of different length DNA, each fragment ceasing at a particular base sequence which shows the position of that base in the DNA polynucleotide. The base sequence of the gene can be read directly from the autoradiograph.

It is not possible to complete the HGP by the study of genetic linkage maps. Although linkage maps are the ‘coarsest resolution’ of gene mapping, they only locate the relative position of a gene on a chromosome, but do not give the genes exact location nor its nucleotide sequence, which is not sufficient enough to complete the human genome, as one of the projects primary goals is to produce a set of maps of not only the ‘relative’ position of the gene, but also the exact position of the gene on a chromosome and the nucleotide sequence of the gene. Collaboration of all three types of mapping is necessary to determine the human genome.

 

[silvermoon]

oh, and thanks for the stuff on the limitations of HGP data malkin

 

[Living_Legend]

Linkage maps are used to isolate genes that cause inherited diseases. They can only exist due to studying families with a genetic disease. Therefore, only these families are studied.
Hence, only hereditary diseases are on linkage maps. The HGP is made up of thousads of genes that dont express disease. Therefore, linkage maps are not appropriate as they dont map all genes.
Hope that helped.

 

[gemgem101]

Death to biology..
But thanks for the sharing.. x

 

[jackydoll]

Just thought I'd do a little sharing..

Goals
– detailed maps of the genes in the human genome
- Determining the complete nucleotide (base) sequence of DNA of each gene (e.g. GAC)
- Identifying the genetic variation in the human genome
- Identifying and addressing the ethical, legal and social issues related to the HGP.

Limitations
- Data from the HGP are in the form of base sequences (e.g. GAC GGG GGC AAT GCT) and are meaningless on their own – they need to be interpreted.
- A small proportion of the base sequence of each chromosone consists of genes, so it is necessary to search the sequence for possible genes. After identifying a possible gene the next tasks include identifying the protein made from the gene, finding where the gene is expressed in the human body, what does the gene control, when and under what conditions is the gene active.
- To identify possible genes from the DNA sequence data, the scientists search the sequences for lengths of DNA that correspond to possible genes. The rapid scanning of base sequences has been made feasible through the use of computers and specialised software. Genes vary in size, but an average gene consists of several thousand bases.
- A possible gene is a sequence of dna that begins with a start triplet (TAC or GTA), can be read in successive triplets that code for at least 100 amino acids without stopping, ends with a stop triplet (ACT, ATT, or ATC). After identifying the gene, a protein product must be identified and its function.

nice